1. Field of the Invention
The disclosures herein generally relate to an image output system, an image signal generation apparatus and a recording medium. To be more in detail, the disclosures herein relate to an image output system, an image signal generation apparatus and a recording medium that stores a program, for outputting images by switching inputs of multiple channels.
2. Description of the Related Art
In recent years, projectors have made progress in terms of variety of available input sources. For example, some projectors are compatible with various video interfaces such as VGA (Video Graphics Array), HDMI (High-Definition Multimedia Interface), DVI (Digital Visual Interface), and DisplayPort (registered trademark). Also, some projectors are capable of projecting an image via a network using a network connection by a wired line or a wireless LAN, or are capable of projecting an image from a file stored in a USB (Universal Serial Bus) storage.
As the above progress is made in terms of the variety of available input sources, it has become difficult for a user to keep track of which input source is currently being used, and it has become cumbersome for a user to change channels. In order to save this kind of effort, some related-art projectors are provided with the function to search for a channel that has an input signal, and to switch the input source to the channel that has the input signal. By this, it becomes easy to select a source that is outputting signals and to project images.
For example, in Patent Document 1, a technology, whose object is to perform an auto-search and a video input terminal selection in a projection apparatus that has multiple video input terminals, is disclosed. In the projection apparatus according to Patent Document 1, an input key is included in a remote controller. When the input key is pressed by “short-pressing”, an auto-search is triggered and an input is automatically switched to the video input terminal that has an input signal. On the other hand, when the input key is pressed by “long-pressing”, signal names of the video input terminals are displayed one by one in sequence in a predefined period of time, and the video input is switched to the video input terminal whose signal name is displayed when the input key is released.
In the meantime, in the above projection apparatus, there may be a case where an alarm display screen related to the current projection is to be reported to a user. Such a case includes, for example, a case where, during a projection of a file in the USB storage, an error occurs in the USB storage or the USB storage is removed. At this time, if an auto-detection function such as the auto-search of Patent Document 1 is activated, then there is a possibility of a problem in which the above alarm display screen cannot be displayed appropriately.
For example, if an error occurs in the USB storage or the USB storage is removed, then as a response, the USB storage is un-mounted. Even if there is an error display screen regarding an input signal that should be reported to the user, the input signal is determined to exist by the auto-search only when there really exists the input signal. Therefore, as the USB storage is un-mounted, it is determined that the input signal does not exist in the channel for which the error display screen should be displayed, and the input channel is switched to another channel in which the input signal is determined to exist. As a result, the alarm display screen related to an error in the USB storage or to the removing of the USB storage is not reported to the user, and there is a possibility that the error is not noticed by the user and left unresolved.    [Patent Document 1] Japanese Patent Application Publication No. 2007-327987